Mishka, prayer is always the first place to go. I don't really know what to recommend, although my situation is similar only to the extent that my W walked away from all of our bills. The thing that is in my favor is that I was the breadwinner and pretty much took care of all the bills anyway. She would bring in an occassional paycheck which was a blessing but I tried to keep expenses controlled. It is getting tight now though because of the house we moved into, thinking there would be two incomes to pay down the second mortgage.
I think you need to do what is necessary to take care of you and your son. When you do anything try to remove any anger or retaliation out of it. Your H will be upset no matter what but when he is rational, he will understand and respect you for doing what was necessary.
Me:56, W:51 D:26,S:24,S:22 Married:18 Bomb 9/27/06 Separated 11/27/06 Divorced 10/6/08 Leaving it up to God